Acta Entomologica Sinica (2007) 50, 920-926

Xiao-Yi Wang, Zhong-Qi Yang, Hui Wu, Song-Jun Liu, Hong-Yan Wang and Ling Bai (2007)
[Parasitism and reproductive biology of Spathius agrili Yang (Hymenoptera Braconidae)]
Acta Entomologica Sinica 50 (9), 920-926
Abstract: Spathius agrili Yang (Hymenoptera : Braconidae) is an important natural enemy parasitizing larvae of the emerald ash borer (EAB) , Agrilus planipennis Fairmaire ( = A. marcopoli Obenberged (Coleoptera Buprestidae) , in Tianjin, China. The survival time of S. agrili under different nutrimental conditions, egg productions of the parasitic wasp at different periods, influence of host size on the development of wasp offspring, and utilization of host beneath the bark of different thickness, were investigated in fields, combining with observations in the laboratory. The results showed that the survival days of the parasitoid differ significantly under different nutritional conditions. Wasps can live pronouncedly longer after feeding 20% honey dilution with the maximal survival time of 3 months, and under the same conditions females usually can survive a little longer than males. When supplied with nutrition the maximum period for oviposition of the braconid is up to 8 weeks with the peak around the 2nd week. During the whole oviposition period, the mean egg production of 8 - 12 eggs per female per week is almost constantly maintained without high fluctuation. The newly hatched larvae of S. agrili may produce venoms and attack host initiatively, so help to improve the survival opportunities of parasitoid progeny. The number of successfully developed parasitoid offspring from host enhances with the increase of host larval weight, which indicates that the host nutrition capacity affects the development and survival of wasp progeny. S. agrili can utilize those hosts at right ages beneath the bark of 1 - 6.5 mm in thickness. Approximately 92% EAB larvae parasitized by Spathius are distributed at 1 - 4 mm thickness of the bark with the peak at 3 mm. Relationship between the number of wasps and bark thickness can be simulated with a quadratic parabola roughly, and the theoretical maximum number of the parasitoid would be expected at 3.97 mm thickness of the bark.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
(original language: Chinese)
Database assignments for author(s): Xiao-Yi Wang, Zhong-Qi Yang

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
general biology - morphology - evolution

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Agrilus planipennis		China (NE)
Spathius agrili (parasitoid)	Agrilus planipennis		China (NE)